EM250-RCM-R Ember, EM250-RCM-R Datasheet - Page 24

• Manufacturer Part Number: EM250-RCM-R
• Description: EM250 RCM BOARD
• Manufacturer: Ember
• Type: Transceiver, 802.15.4/ZigBeer

Specifications of EM250-RCM-R

• Frequency: 2.4GHz
• For Use With/related Products: EM250
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 636-1023

EM250
120-0082-000S
Parameter
Frequency
Duty cycle
Phase noise from 1kHz to 100kHz
Accuracy
Crystal ESR
Crystal ESR
Start-up time to stable clock (max. bias)
Start-up time to stable clock (optimum bias)
Current consumption
Current consumption
Current consumption
Parameter
Frequency
Accuracy
Load capacitance (18pF on OSC32A and 27pF on
OSC32B)
Crystal ESR
Start-up time
Current consumption
Table 12 lists the specifications for the high-frequency crystal.
4.11.2 Low-Frequency Oscillator
The optional low-frequency crystal source for the EM250 is a 32.768kHz crystal. Table 13 lists the require-
ments for the low-frequency crystal. The low-frequency crystal may be used for applications that require
greater accuracy than can be provided by the internal RC oscillator. When using the internal RC Oscillator, the
pins OSC32A and OSC32B can be left open (or not connected). If the designer would like to implement the low
frequency clock source with an external digital logic source, then the OSC32A pin should be connected to the
clock source with OSC32B left open.
The crystal oscillator has been designed to accept any standard watch crystal with an ESR of 100 kΩ (max). In
order to keep the low frequency oscillator from being overdriven by the 32.768kHz crystal, Ember recom-
mends the PCB designer asymmetrically load the capacitor with 18pF on OSC32A and 27pf on OSC32B. For
more information on this design recommendation, please review document 120-5026-000_Designing with an
EM250.
Table 12. High-Frequency Crystal Specifications
Table 13. Low-Frequency Crystal Specifications
Test Conditions
Initial, temperature, and aging
Load capacitance of 10pF
Load capacitance of 18pF
Good crystal: 20Ω ESR, 10pF load
Worst-case crystals (60Ω, 18pF or
100Ω, 10pF)
At maximum bias
Test Conditions
Initial, temperature, and aging
At 25°C, VDD_PADS=3.0V
Page 24
- 100
Min.
Min.
- 40
40
32.768
Typ.
Typ.
12.5
0.2
0.6
24
+ 100
Max.
- 120
Max.
+ 40
100
100
0.3
0.5
60
60
1
2
1
1
dBc/Hz
Unit
MHz
Ppm
Unit
Ppm
kHz
mA
mA
mA
kΩ
Ms
Ms
pF
μA
Ω
Ω
%
S